Grain moisture is of primary importance for maize (Zea mays L.) production and breeding. Low (or reduced) grain moisture decreases the economic impact of artificial drying and allows earlier harvesting, which permits the grower to obtain a higher price for the crop at an earlier date and reduces exposure of the crop to adverse weather and field conditions that hinder the harvest operation (Sweeney et al (1994) Crop Sci 34:391-396). Warmer temperatures and lower humidity promote rapid field drying of corn grain. However, in mid- to short-season environments, harvest time is often characterized by decreases in temperature and increases in humidity. Thus, hybrids with superior yielding ability that dry at a more rapid rate are highly desirable.
Historically, selection of inbred lines to produce hybrids with reduced grain moisture has been performed by measuring grain moisture directly. However, some studies have suggested that grain moisture can also be selected for indirectly by measuring traits such as field grain drying rate (FDR) (Sala et al (2006) Theor Appl Genet 112:462-471) or husk senescence (Sweeney et al (1994) Crop Sci 34:391-396). Silking date and black layer formation were also found to be significantly correlated with grain moisture in some studies; however, other studies have shown a limited association (Sweeney et al (1994) Crop Sci 34:391-396). The use of any phenotypic selection method can require extensive resources and is somewhat imprecise, with environmental factors and complex associations between different agronomic traits complicating selection.
Selection through the use of molecular markers associated with reduced grain moisture allows selections based solely on the genetic composition of the progeny. As a result, plant breeding can occur more rapidly, thereby generating commercially acceptable maize plants with reduced grain moisture in a relatively short amount of time. Thus, it is desirable to provide compositions and methods for identifying and selecting maize plants with reduced grain moisture. These plants can be used in breeding programs to generate high-yielding hybrids that dry at a more rapid rate.
QTL for grain moisture have been reported on chromosome 9 (Frascaroli et al. (2007) Genetics 176:625-644; Sala et al. (2005) Theor Appl Genet 112:462-471; Blanc et al. (2006) Theor Appl Genet 113:206-224; Moreau et al. (2004) Theor Appl Genet 110:92-105; Lu et al. (2003) Theor Appl Genet 107:494-502; Austin et al. (2000) Crop Sci. 40:30-39).